Control for automatic transmission

ABSTRACT

The present invention relates to a control for automatic transmission of a vehicle wherein the computation of the slip ratio may be established by any one of, mechanical means, means utilizing fluid under pressure, or electrical means; there being associated in combination therewith, a computing circuit which is applied for the determination of the number of revolutions of the engine of the vehicle, the number of revolutions of the output shaft of the torque converter or the power driven shaft of the drive unit of the vehicle, and there being additionally applied in connection therewith a logic product circuit, a logic sum circuit, a bistable memorial circuit and a synchronous time retaining circuit for effectuating the operation of electrically actuable distribution valve means to control the transition from high- to low-gear functions and vice versa for the vehicle.

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ttes ate E Shirai et al.

3,354,744 ll/l9o7 CUNTRQL FOR AUTUMIATIC TRANSMISSION Inventors: 'lalreaki Shirai, Nagoya-shi; Shigeru Salcaltibara, Chita-gun, Aichi-ken;

Masaalki Nogucbi, Nagoya-shi; Masaharu Sumiyoshi, Toyota-shi, a]! of Japan Assignees: Toyota Jidosba Kogyo Kabushiki Kaisha;

Nippon Dense Kabushilti Kaisha Filed: Sept. 5, 1969 Appl. No.: 855,510

Foreign Application Priority Data Kuhnle et al ..74/752 A Feb. 8, i972 3,439,564 4/1969 Scholl et al.. ..74/752 A 3,448,640 6/1969 Nelson ..74/752 A Primary Examiner-C. J. l-lusar v Attorney-Blum, Moscovitz, Friedman 8:. Kaplan ABSTRACT The present invention relates to a control for automatic transmission of a vehicle wherein the computation of the slip ratio may be established by any one of, mechanical means, means utilizing fluid under pressure, or electrical means; there being associated in combination therewith, a computing circuit which is applied for the determination of the number of revolutions of the engine of the vehicle, the number of revolutions of the output shaft of the torque converter or the power driven shaft of the drive unit of the vehicle, and there being additionally applied in connection therewith a logic product circuit, a logic sum circuit, a bistable memorial circuit and a synchronous time retaining circuit for effectuating the operation of electrically actuable distribution valve means to control the transition from highto low-gear functions and. vice versa for the vehicle.

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1. In a variable speed automatic transmission for a vehicle having an engine having an output shaft, a gear unit providing a plurality of different speed gear ratio drives and having an output shaft, a hydraulic torque converter having input and output interposed therebetween, friction engaging means including fluid-actuated motors which complete the respective gear ratio drives, a source of fluid under pressure, delivery conduit means for connecting said source of fluid under pressure with said motors including a manual selecting value for supplying the fluid under pressure in certain conduits and distribution valve means for selectively supplying the fluid pressure in certain conduits to respective motors, and electrically operable means for activating said distribution valve means; the combination of first and second slip ratio computing means for generating an electric signal when the ratio of the revolving velocity of the output shaft of said torque converter to the revolving velocity of the input shaft of the same attains different predetermined values, a first and second revolving velocity detecting means for the output shaft of said engine for generating an electric signal when the revolving velocity of the output shaft of said engine attains a different revolving velocity, first and second revolving velocity detecting means for the output shaft of said gear unit for generating an electric signal respectively when the revolving velocity of the output shaft of said gear unit attains a different revolving velocity, gear position indicating means for generating an electric signal for indicating each position of the other gear ratio drives of said gear unit when one of said gear ratio drives is selected, a synchronous time retaining circuit for generating an electric signal when a predetermined time expires after said distribution valve means has been activated, a first logic product circuit for generating an electric signal when the electric signals generated (a) by said first slip ratio computing means, (b) said first revolving velocity detecting means for the output shaft of said engine, (c) said first revolving velocity detecting means for the output shaft of said gear unit, (d) said gear position indicating means and (e) said synchronous time retaining circuit are coexistent, a second logic product circuit for generating an electric signal when one of the electric signals generated (a) by said second slip ratio computing means, (b) said second revolving velocity detecting means for the output shaft of said engine or second revolving velocity detecting means for the output shaft of said gear unit, (c) said gear position indicating signal and by (d) said synchronous time retaining circuit are coexistent; whereby said electrically operable means for said distribution valve means activated in one direction by the generation of the electric signal by said first logic product circuit to carry out the gear ratio drive from lower gear state to the higher gear state is activated to its original state by the generation of the electric signal from said second logic product circuit to carry out the gear ratio drive from higher gear to the lower gear state.
 2. In a variable speed automatic transmission for a vehicle, the combination according to claim 1 characterized in that a logic sum circuit is provided for generating an electric signal when one of the electric signals generated by (a) said second slip ratio computing means, (b) said second revolving velocity detecting means for the output shaft of said engine or said second revolving velocity detecting means for the output shaft of said gear unit is present; whereby said second logic product circuit generates an electric signal when the electric signals generated by said logic sum circuit, said gear position indicating means and said synchronous time retaining circuit are coexistent.
 3. In a variable speed automatic transmission for a vehicle the combination according to claim 2 characterized in that a bistable memorial circuit generates an electric output signal when an input signal applied to its first input terminal and eliminating said electric output signal, when another input signal is given to its second input terminal, is provided by connecting its first input terminal to the output terminal of the first logic product circuit and connecting its second input terminals of the first logic product circuit and connecting its second input terminal to the output terminal of the second logic product circuit; whereby said electrically operable distribution valve means is actiVated in one direction from its position by the generation of the electric output signal from said bistable memorial circuit to change of the gear ratio drive from the lower gear state to the higher gear state and is directionally returned to its original position by the elimination of the electric output signal from said bistable memorial circuit, to effectuate the gear ratio drive from the higher gear state to the lower gear state.
 4. In a variable speed automatic transmission for a vehicle having an engine, having an output shaft, a gear unit having an output shaft providing a plurality of different speed gear ratio drives, a hydraulic torque converter having an input and output interposed therebetween, friction engaging means including fluid-actuated motors which complete the respective gear ratio drives, a source of fluid under pressure, delivery conduit means for connecting said source of fluid pressure with said motors including a manual selecting valve for supplying the fluid under pressure in certain conduit means and a plurality of distribution valves for selectively supplying fluid under pressure to respective motor or motors and electrically operable means for respectively activating said distribution valves; the combination of a plurality of electronic computing circuits for generating an electric output signal for operating said distribution valves, a synchronous time retaining circuit for generating an electric signal when a predetermined time expires after said distribution valves being activated, gear ratio indicating means for generating an electric signal for indicating each gear position of the different gear ratio drives of said gear unit when one of said gear ratio drives is selected; each one of said electronic computing circuits being provided with first and second slip ratio computing means for generating an electric signal (a) when the ratio of the revolving velocity of the output shaft of said torque converter to the revolving velocity of the output shaft of said torque converter to the revolving velocity of the input shaft of the same reaches a predetermined value, (b) the first and second revolving velocity detecting means for the output shaft on said engine for generating an electric signal when the revolving velocity of the output shaft of said engine reaches to predetermined velocity, (c) a first and second revolving velocity detecting means for the output shaft of said gear unit for generating an electric signal when the revolving velocity of the output shaft of said gear unit attains a predetermined velocity; a first logic product circuit for generating an electric signal when the electric signals generated by (a) said first slip ratio computing means, (b) said first revolving velocity detecting means for the output shaft of said engine, (c) said first revolving velocity detecting means for the output shaft of said gear unit, (d) said gear position indicating means and (e) said synchronous time retaining circuit are coexistent; a second logic product circuit for generating an electric signal when one of the electric signals (a) generated by said second slip ratio computing means, (b) said second revolving velocity detecting means for the output shaft of said engine or second revolving velocity detecting means for the output shaft of said gear unit, (c) said gear position indicating means and (d) said synchronous time retaining circuit are coexistent; whereby said electrically operable means for said distribution valves are activated for displacement in one direction by the generation of the electric signal by said first logic product circuit and are activated to return to their original state by the generation of the electric signal by said second logic product circuit to complete the respective gear ratio drives.
 5. In a variable speed automatic transmission for a vehicle, the combination according to claim 4 is further characterized in that there are provided a logic sum circuit among said logic computing circuits for generating an electriC signal when one of the electric signals generated by (a) said second slip ratio computing means, and (b) said second revolving velocity detecting means for the output shaft of said engine or said second revolving velocity detecting means for the output shaft of said gear unit is applied; and a bistable memorial circuit among logic computing circuits which continues generating an electric signal when an electric output signal generated by said first logic product circuit is applied to its first input terminal and continues eliminating said electric output signal when an electric output signal generated by said second logic product circuit is applied to its second input terminal; whereby said electrically operable means respectively is activated in one direction by the generation of the electric output signal from said bistable memorial circuit and is returned to its original state by the elimination of the electric output signal from said bistable memorial circuit. 